If I recall, there was a change in the ext2 utilities from FC3 to FC4 which fsils with earlier distro created partitions.
I believe you need to disable filechecking with the entries in your fstab file. That is, change the last two digits in your older distros to zero. Alternatively, you could mount the other OS partitions whenever you need to access the files on the common partitions..
Are you talking about a common /home partition?
Yes, and therefore, I can't use my privous installations anymore. And I have no idea, how to convert the ext3 back.
I have read already bug #174618, but they assume a kernel patch for FC4. But as I want to use Centos4 and don't believe RedHat will corporate such a patch into their Kernels.